Tappet construction



1940. c. VOORHIES EIAL 2,227,238

TAPPET CONSTRUCTION Original Filed Aug. 3, 1936 2 Sheets-Sheet 1 Dec.3l,1940. c. VOORHIES ET AL TAPPET CONSTRUCTION Original Filed Aug. 3, 19562 Sheets-Sheet 2 Patented Dec. 31, 1 940 TAPPET CONSTRUCTION CarlVoorhies and Harry E. Voorhies, Detroit, Mich, assignors to EatonManufacturing Company, Cleveland, Ohio, a corporation of Ohio Originalapplication August 3, 1936, Serial No. 94,040. Divided and thisapplication July 21,

1939, Serial No. 285,766

4 Claims. (01. 123-90) This invention relates to automatic compenbecomeapparent from the following description sating tappets for operatingsuch parts as intake and appended drawings. or exhaust valves ofinternal combustion engines, For the purpose of illustrating the genusof and more especially relates to improvements in the invention, typicalconcrete embodiments are the construction and arrangement of tappets ofShown in the a c mpa yi d aw n s in whi h such character, and is adivision of our appli- Fig. 1 is a central vertical section of a tappetcation for Letters Patent of the United States construction according tothis invention; for improvements in Tappet construction, filed Figs. 2and 3 are transverse sections taken August 3, 1936, serial No. 94,040now Patent No. substantially on the lines 2-2 and 3-3 of Fig. 1;2,185,991, issued Jan. 2, 1940. Fig. 4 is a section showing a portion ofan in- The principal object of the invention is to ternal combustionengine and showing a tappet improve the automatic compensating mechanismuch'as illus r ted in F 1 to 3 inte p ed eof tappets especially adaptedfor operating movatween the valve operating cam and a spring ble partsof internal combustion engines. Seated intake exhaust Valve; Anotherobject is to provide in a device of the 5 is a fragmentary V w Similar oF 1 above character a novel check valve construction of a portion of a mifi f rm f pp nand arrangement or such nature that the check struction;an

valve means is closed by a force substantially Figs. 6 and 7 a e v e s mar o 1 Of equal to the force exerted by the engine valve other modifiedforms of tappets constructed acoperating gear when the engine valve isopen. cording to the principles of this invention. r A further object isto provide a novel plunger Referring o t e drawings w r n likenuconstruction for hydraulic compensating tappets merels are pp t like ps n the several which includes means providing a seal between views, andreferring e e pe y to Figs. 1, 2 the plunger and its cylinder, and aninlet port and 3. there s sh w a y a l mp nsa in and a check valve meansfor the hydraulic comeppe s u t C mp ng a cylindrical pensating chamberof the tappet. y a p u a plunger spring l3, a It is also an object ofthe invention to provide coined or o ved alve I in the formof a for auniform rate of leakage from the hydraulic washer, a plain or fiatwasher l5, and a yieldcompression chamber of the tappet and to employable but substantially incompressible washer or o a single elementadapted to abut a plain surface similar packing element l6 formed or aductile for controlling such leak-down rates so that a met ln the b veWa e elements 80 single element may be accurately manufactured nd s a epreferably, although n t n c a y. by a coining or stamping process.maintained in position on the plunger I2 by Another object is to providea system of conmeans 0! 'D a e Was er I"! and a u struction whichobviates the necessity of selective packing spring I8.

or other accurate fitting of plunger parts with he t pp t y H isprovided with an annular respect to the cylinder therefor. recess 20 andone or more liquid admission ports A still further object of theinvention is to 2! leading h r f om t the l n i udinal bore 22 provide,in a tappet construction including a or the tappet body q d y be dmit edcylindrical body and a plunger arranged therein; through e e s 20 andDori; P ts into for a mechanical hysteresis effect, 1. e. a lagging elongitudinal bore from a uitab e source or retardation of the movementof the plunger of liquid S pp y, S c s a lubricating ystem of relativeto its cylinder when forces acting axially an n l Combustion n e lowerend upon the tappet ends are changed. oi. the tappet body II is closedas indicated at 23 Another object is to providejin a tappet conand ispreferably provided with a hard wearstruction, including a cylindricalbody and a Piece 4 a apted to engage the operat ng cam plunger arrangedtherein for defining in onfor an exhaust or intake valve of an internalJunction with said cylindrical body a hydraulic combustion engine- Theupper d 1 the cylincompression chamber, means for efiecting a subdrioaltappet body II is p f h reception stantially complete seal between saidplunger 0f the Plunger l1 a the letter is provided with and cylindricalbody, and means for permitting a cylindrical portion 25 adapted to makea free a definite and predetermined leakage or escape sliding fit withinthe bore 22. The cylindrical of liquid from said hydraulic compressionportion 25 is provided primarily for guiding purchamber. poses. Thespring I8 is arranged in a slightly N Other objects, features andadvantages will compressed condition between the outer headed g end ofthe plunger l2 and the upper open end of the tappet body II for urgingthe plunger l2 outwardly with respect to the bottom of the bore 22. Theplunger I2 is provided with an annular flange 26, thelower face ofwhich, indicated at 21, is substantially normal to the axis of theplunger |2. The upper surface 28 of washer I5 is also a plain surfaceand the cooperating surfaces 21 of flange 26 and 28 of washer I41 areboth machined and polished so that when the washer is pressed upwardlyby any material force leakage between the flange 26 and washer I4 isprevented.

The space 30 within the bore 22 of the tappet body between thecylindrical portion 25 of plunger l2 and the valve member or washer |4constitutes a preliminary or reserved liquid supply chamber for thetappet. The space within the bore 22 of tappet body between the valvemember or washer l4 and the bottom of the bore 22 constitutes thehydraulic compression chamber 3| of the tappet. Expansion of the spring|3 tends to cause the plunger |2 to move outwardly with reference to thetappet body until the end of the plunger |2 contacts the end of thevalve 33, as indicated in Fig. 4, and to cause end 23 of tappet body IIto contact the valve operating cam, or the upper end of the plunger |2and thelower end of the tappet body contact other parts of valveoperating mechanism. Outward movement of the plunger with reference tothe tappet body creates a partial vacuum condition within thecompressionchamber 3| and causes the upper surface 28 of the valvemember or washer M to separate from the surface 21 of flange 26 andpermits flow of liquid from the preliminary or reserved chamber 30 tothe hydraulic compression chamber 3| until the latter chamber is filledwith liquid and the pressure becomes substantially equalized between thechambers 30 and 3|.

The lower face of the valve member or washer I4 is provided with aspiral groove 32 leading from its interior periphery to its outerperiphery as indicated in Figs. 1 and 3. In actual practice this grooveis of very small dimensions, and may be of other form than spiral wherethe desired resistance to flow can be obtained. The spiralling orotherwise lengthening of the groove 32 permits the same to be ofsufficient length to afford the desired resistance to flow of liquidfrom the interior to the outer periphery of the valve member and stillpermit the groove 32 to be formed by mechanical'processes with a desiredaccuracy so that a definite cross-sectional area and length of groove 32may be had. This enables commercial production of grooved washers orvalve members by coining or stamping processes so that definite leakdownrates can be obtained for large numbers of tappets with a result thatuniform operation of all of the tappets will be obtained. The washer I5is preferably composed of metal and has its upper and lower surfacesplain and parallel, and these surfaces are machined and polished so thatundesired or inadvertent leakage between the surfaces thereof and thesurfaces with which they cooperate will not occur. The upper surface ofthe washer I5 cooperates with the grooved surface of the valve member orwasher |4 so that the groove 32 provides a small cross-section passagepreferably of extended length, the cross-sectional area and length ofthis passage 32 being uniform for all tappets of, the same typeproduced.

The washer is composed of a soft metal such asv lead or soft alloys,such metal inherently having,

of course, a high degree of ductility. The inner ing washer l6, washeri5 and valve member H in position. The spring 3 is very light so thatany material difference in pressure between the preliminary chamber 30and the hydraulic compression chamber 3| will allow admission of liquidbetween the cooperating surfaces 21 and 28 of the flange 26 on plungerl2 and the valve member I4, provided the lesser pressure occurs in thehydraulic compression chamber 3|.

During operation the tappet illustrated in Fig. l, is interposed in avalve operating mechanism in 'the manner indicated in Fig. 4. Oil may beadmitted through the annular recess 20 and ports 2| to the preliminaryor reserve chamber 30, from the conventional lubricating system of theinternal combustion engine. Plunger spring l3 holds the upper end ofplunger l2 against the valve stem, or an operating part therefor, andthe closed end 23 of the tappet body against the cam shaft, or partoperated thereby. When the plunger spring l3 causes outward movement ofthe plunger with reference to the tappet body a partial vacuum conditionwill be created within the hydraulic compression chamber 3| and thevalve member M will not be held in tight engagement with the shoulder 26on plunger |2. Oil then flows between the cooperating surfaces 21 and 28of the flange 26 on plunger l2 and the valve member M from thepreliminary chamber 30 to the hydraulic compression chamber 3| When thepressures are substantially equal in the chambers 30 and 3|, the washeror valve element M will be brought into contact with the surface 21 offlange 26 by the action of the light packing spring l8. As the cam shaftlifts the tappet body, the pressure of the oil in the hydrauliccompression chamber 3| is increased on two faces of the packing element6, the inner peripheral surface and the lower surface of the packingelement I6, and will tend to radially expand the packing element andforce it outwardly against the wall of the bore 22 of the tappet bodyand will also force it against the washer |5.. The ductility of thematerial from which the packing element is constructed is such that thepacking element IE will actually be expanded into contact with the wallof the bore 22 of tappet body M if not already in contact therewith, andwill be maintained in firm contact therewith if already in contact withthe wall, so as to effect a seal between the packing element and thetappet body, and the pressure of the sealing element against the washerl5 will effect a seal between these elements. This upward pressure istransmitted to the washer |-5 forcing the latter into tightengagement'with the valve member I4 so that no leakage can occur fromthe inner periphery of the valve member [4 to the outer peripherythereof except such leakage as is allowed by the spiral groove 32. Thisupward pressure likewise forces the smooth plain upper face 28 of thevalve |4 against the corresponding face 21 on the flange 26 of plunger|2. since the valve member I4 is pressed against the flange 26 by aforce substantially equal to the entire load of the valve gear at thetime of opening of the engine valve, a seal between the valve member 14and flange 26 is effected. When the engine valve is in closed positionthe pressure holding the valve member l4 against the shoulder 26 isreleased so that oil can see'p between the surfaces of the washerdraulic compression chamber to the reserve supply chamber 30 withouthaving the cross-sectional area of the groove too small formanufacturing purposes. During lift of the engine valve the grooved faceof the valve member I4 is pressed against the flat smooth face of thewasher l5 by a force substantially equal to the. entire load of thevalve operating mechanism. In this manner, the engine valve will beelevated without appreciable lift loss except that provided for by thegroove 32 which controls the leak-down rate of oil flow between thehydraulic compression chamber 3| and the preliminary or reserve chamber30.

As previously indicated the packing element or washer I5 is composed ofyieldable ,or expandible metal of alloy of highly ductile character. Theclearance between the inner periphery of the packing element l6 and thecylindrical portion of the plunger l2 surrounded thereby, is preferablyquite small so that the packing element I6 is maintained in asubstantially confined condition between the plunger I2, the washer 15,the wall of bore 22 of tappet body H and the packing washer I! on theoil within the hydraulic compression chamber 3|.

With the packing washer IS in a substantially confined condition,elevation of the tappet by operating cam shaft therefor will increasethe pressure within the hydraulic compression chamber 3| and cause thepacking element l5 frictionally to grip the wall of the bore 22 oftappet body H so as to cause a lagging or retardation in movement of theplunger (2 relative to the tappet body II when forces acting axiallyupon opposite ends of the tappet are changed. The packing element IEwill produce a mechanical hysteresis effect in that it causes a laggingor retardation of relative movement between the plunger l2 and tappetbody II when forces acting axially upon the ends of the tappets aresubjected to changes. The magnitude of this effect may be controlled byvarying the clearance between the inner peripheral surface of thepacking element l6 and the cylindrical portion of plunger l2 which thepacking element sur rounds. This mechanical hysteresis effect of thepacking element IE will quiet the operation of the tappet and willsubstantially obviate any possibility of the tappet bouncing orchattering with reference to the operating cam therefor.

Reference may now be had to Fig. 4 which illustrates a tappet of theconstruction described relative to Fig 1, interposed. between a valve 33of an internal combustion engine and an operating cam 34 fixed to camshaft 35. 'The' operation of this arrangement will be clear from theabove description of the construction shown in Fig. 1. Referring to Fig5; a construction very similar to that disclosed in Fig. l isillustrated. In this construction the only modification is in theplunger I2 and relates to the manner in which the lower end of thepacking spring I8 is connected to the plunger. In the construction shownin Fig. 5 an "element 36 is press fitted upon the reduced end 31 ofplunger 12' in order to retain the lower end of packing spring i 8connected to'the plunger l2 instead of clipped in a groove in the lowerend of the plunger in the manner illustrated in Fig. 1. Thisconstruction, like that shown in Fig. 1, providesa yieldable packingelement l6 of ductile material adapted to be maintained in sealingcontact with the wall of the bore of the tappet body If by the highpressures in the hydraulic compression chamber 3! for substantiallysealing the plunger 12 with respect to the tappet body ll. Such highpressures also cause the packing element I6 to be forced into andmaintained in sealing engagement with the washer l5 and the valve memberH to effect a seal with the flange 26 of plunger l2. The coined orgrooved surfaceof valve member l4 and the upper surface of the washer l5are also 7 brought into contact so that the spiral groove in the lowerface of valve member |4 affords means for allowing only a definite andpredetermined leakage or escape of oil fromthe hydraulic compressionchamber .3l. The construction of the remaining elernents and theirarrangement is the same as that illustrated in Fig. 1.

Reference may now be had to Fig. 6 which illus- I trates a modifiedformof tappet construction.em-

bodying the principles of the present invention, this constructionincludinga cylindrical tappet body 4| provided with a bore 42, whichaffords the shoulder 43 for supporting a separatecylinder 44 adapted tobe received within the upper end of the bore 42. I z

The tappet body is provided with an annular recess 45 and an admissionport 46 and isotherwise of substantially the same construction as thatdisclosed in the embodiment shown in Figs. 1 and 5. The separatecylinder 44 is provided with a cylindrical bore 41 and a reduced andbored boss portion50 in which has been press fitted a suctiontube 5| anda valve retaining cage 52. A ball check valve 53 is disposed within thecage 52 for limited movement therein and is adapted to make a fine linecontact with the upper end of the bore of suction tube 5|, so that theupper end of the bore Wall of tube 5| forms the valve seat. for thereturn valve 53. The upper end of the cage 52 is provided with an oilpassage 54. The separate cylinder 44 preferably makes a drop or slidingfit within the upper end of the bore 42 so that air may be vented fromthe preliminary or reserve liquid supplychamber 55 formed bythat part ofthe bore 42 which lies below the separate cylinder 44. The tappetplunger56 makes a loose Or-sIidingfit within the bore 41 of separatecylinder 44.; A cylindrical washer member 51 makes a similar fit withinthe bore 41 of separate cylinder 44 and is arranged within the latterbore immediately below the plunger 56. A packing washer 1 v 60 of thesame character as the washer I6 previously described and a packingretainer washer 5| are arranged within the bore 41 below the plunger 56and washer 51 in the order named. A coil spring 62 is interposed betweenthe boss portion 64 of the. tappet.

During the operation of this tappet construction, oil Orotherliquidunder pressure is adcompression chamber mitted through the annularrecess 45 and port ll to the preliminary or reserve supply chamber 5!.The plunger spring I! causes'extension of plunger I until the lattercontacts one valve operatins part and the closed endof the tappet body4i contacts anothervalve operating part. Outward movement of the plunger56 creates a partial vacuum condition within the hydraulic compressionchamber 64 causing the valve 53 to lift from its seat and liquid mediumto be drawn upwardly through the suction tube 5| into the hydraulic 64of the tappet. when an' engine valve is lifted by the tappet, theincreased pressure within the hydraulic compression chamber 64 isexerted upon the inner periphery of the yieldable packing element 60 andupon the lower surfaceof the latter, tending to cause the material ofthe packing to flow outwardly and provide a seal between the packing andthe bore 41 of the separate cylinder 44. The increased pressure exertedby the liquid medium within the hydraulic compression chambercauses theadjacent surfaces of washer 51 and the yieldable packing element to tobe pressed together and the upper surface of washer 51 and the lowersurface of plunger 56 likewise to be brought into intimate contact. Thesurfaces are pressed together by a I force substantially equal to theentire load of the valve operating gear at the time of opening of theengine valve. The leak-down rate between the plunger and separatecylinder is controlled by the lowersurface of the plunger 56 and theupper surface of the washer 51, one of the surfaces either being groovedas indicated at 32 in the construction shown in Fig. 1 or one or more ofthese surfaces being left in a suiliciently roughened condition, notpolished, to provide the proper leakdown rate between theplunger and theseparate cylinder. In this construction the yieldable packing element 60is substantially confined by the washer SLseparate cylinder 44, thepacking retainer washer BI and the oil or other liquid medium within thehydraulic compression chamber 64. Thus the 'yieldable or ductile packingelement 60 aflords substantially the same mechanical hysteresis efiectin producing a lagging or retardation of movement of the plunger withreference to the separate cylinder when axial forces directed againstopposite ends of the tappet are varied as in the previously describedconstructions. The

ball valve 53 is gravity and inertia actuated as well as by differentialfluid pressures to cause its return to and maintenance in seatedposition during lift of the tappet;

Referringto Fig. 'l, a tappetvery similar in construction to that shownin Fig. 6 is illustrated.

' Inthis construction the plunger 56', corresponding to the plunger 56of the previously described embodiment is provided with a reduced endportioniladaptedto contact a valve stem or other j valve operating partfor an exhaust or intake valve of an internal combustion engine. Anabutmerit sleeve 66 is threaded to the upper end of the separatecylinder 44", corresponding to the separate cylinder 44 of thepreviously described embodiment, and the abutment sleeve 66 is spaced aconsiderable distance from the reduced portion 65 of plunger 56'. Theabutment sleeve 66 limits outward movement of the plunger with referenceto a separate cylinder so that in the event that an engine valve becomesstuck. in open position the plunger cannot follow the stuck valve asuflicient distance to cause breakage of the latter or of the cylinderhead of the engine. The remaining parts shown in Fig. -7 correspond withaaa'naas like parts shown in Fig. 6 and are given the same numerals.

In all of the liminary or reserve air separation chamber .is vented toatmosphere either through clearance between the plunger and the bore ofthe tappet body as in the embodiment shown in Figs. 1 to 5, or throughclearance between the separate cylinder and the bore of the tappet bodyas in the case of the embodiment shown in Figs. 6 and 'l. The ductilepacking elements are forced radially outwardly by flowing the materialthereof ,in that direction in order to seal the plunger with referenceto its cylinder. A mechanical hysteresis effect is afforded by all oftheillustrated embodiments due to forcingthe ductile and yieldablepacking to flow the material thereof outwardly against the wall of itsconfining cylinder, the packing otherwise being substantially confinedby the plunger element or elements carried thereby and the oil in thehydraulic compression chamber of the tappet so as to produce a laggingor retardation in movement of the plunger with reference to the separatecylinder when axially directed forces against the end of the tappet arethe plunger so that operation of the engine valve will be had, althoughwith some lift loss, in the event of failure of oil supply and after oilin the preliminary or reserve supplychamber has been exhausted. In theembodiment shown in Figs.

1 and 5, the lower end of the plunger if or the element 36 abuts theclosed end 23 for limiting inward movement of the plunger with referenceto the tappet body. In the embodiment shown in Figs. 6 and 7 the plungerand elements carried thereby have but a limited movement inwardly withreference to the separate cylinders 44 or .As many changes could be madein the above construction, and many apparently widely differentembodiments of this construction could be had without departing from thescope thereof, it is'intended that all matter contained in the abovedescription or showing shall be interpreted as illustrative and not in alimiting sense.

, What is claimed is:

1. A hydraulic valve tappet, comprising a cylindrical body, providedwith a longitudinal bore, said body being closed at one end and open atthe other, a plunger disposed in said bore and in conjunction with saidcylindrical body defining a hydraulic compression chamber, means for admitting liquid into said cylindrical body and resilient means forextending said plunger outwardly with respect to said cylindrical body,said plunger including an annular flange providing a plain surfacenormal to the axis of said plunger, a plain surface valve discpositioned to, abut at one face thereof the plain surface of said flangeto provide a check valve, the other plain surface of said valve discbeing provided with a groove of small crosssection and extended length,a second plain surface disc positioned to abut the grooved surface ofsaid valve disc to complete a small cross-section passage of relativelylong .lengthfor limiting to a slight amount'leakage from said hydrauliccompression chamber, and a yieldable element formed of a ductilematerial substantially confined by said illustrated embodiments, thepre- 2,927,958 portion slidably engageable with the cylinder walls, acontinuous sealing ring positioned at the end of the plunger bodyadjacent the reservoir and movable with the plunger, said ring having aperipheral portion 01 ductile material engageable with the cylinderwalls to resist the escape of fluid from the reservoir past the plunger,and

- a pressure reliei. member cooperating between the sealing ring and theplunger providing for a limited escape oi fluid past the sealing ring.

3. In a valve tappet, a cylinder having a fluid reservoir therein, aplunger having a body portion slidably engaging the cylinder walls, aseal com- I prising a member of ductile metal having a circular outeredge and positioned at the end of the plunger body adjacent thereservoir with the circular edge slidably engaging the cylinder wallsthroughout the circumference of said edge, said member being movablewith the plunger and having an opening therethrough tor the passage offluid, and means associated between said member and said plungerproviding a restricted by-pass ior fluid escaping through the opening insaid member.

4. In a valve tappet, a cylinder having a fluid reservoir therein, aplunger having a body slidably engageable with the cylinder walls, aseal positioned between the plunger body and reservoir and movable withthe plunger, said seal comprispositioned members having circular outeredge portions, at least one of said members being formed of ductilematerial frictionally engaging ing a plurality of independently movableJuxta-

